taxonID	type	description	language	source
A8FFA03204C15EAEB01157C7E101BEB7.taxon	description	Figs 1, 2	en	Kim Thanh, Nguyen Thi, Anh, Nguyen Diep, Anh, Tran Thi Thuy, Thuy, La Thi, Duc, Nguyen Anh, Long, Tran Duc, Dang, Van-Son (2025): Mallotus thinii (Euphorbiaceae), a new species discovered from the coastal areas of the south-central provinces of Vietnam. PhytoKeys 265: 193-208, DOI: 10.3897/phytokeys.265.166360
A8FFA03204C15EAEB01157C7E101BEB7.taxon	diagnosis	Diagnosis. The new species is similar to M. leptostachyus Hook. f. and M. peltatus (Geiseler) Müll. Arg. in shrub habit, in having alternate to opposite leaves, indumentum of simple and stellate hairs and yellow glandular scales, leaf margin with denticulate glandular teeth, racemose and unbranched inflorescences. However, it can be fully distinguished from those by the deciduous stipules (vs. present), oblanceolate leaf blade (vs. ovate to obovate in M. peltatus, and elliptic in M. leptostachyus), penninerved veination (penninerved or palmate in M. peltatus, and triplinerved in M. leptostachyus), extrafloral nectaries two larger near the base or sometimes 2 – 6 (– 8) along midrib (vs. 2 – 6 small one in M. peltatus and two in M. leptostachyus), stamens 28 – 33 (vs. 25 – 35 in M. peltatus and c. 60 in M. leptostachyus), pistillate flower with sepal 3 (vs. calyx urceolate, caducous in M. peltatus), short style up to 0.4 mm long (vs. 2.8 – 4.5 mm long in M. peltatus, c. 0.2 mm in M. leptostachyus), fruits without spines (vs. with spines in M. peltatus).	en	Kim Thanh, Nguyen Thi, Anh, Nguyen Diep, Anh, Tran Thi Thuy, Thuy, La Thi, Duc, Nguyen Anh, Long, Tran Duc, Dang, Van-Son (2025): Mallotus thinii (Euphorbiaceae), a new species discovered from the coastal areas of the south-central provinces of Vietnam. PhytoKeys 265: 193-208, DOI: 10.3897/phytokeys.265.166360
A8FFA03204C15EAEB01157C7E101BEB7.taxon	description	Description. Dioecious shrubs, rarely monoecious, 0.8 – 1.5 m tall. Young branches flattened, matured branches roundish with longitudinal ridges. Indumentum pubescent on most young parts and inflorescences, composed of simple and stellate hairs and yellow glandular scales. Stipules subulate, c. 2.2 mm long, pubescent outside, deciduous. Leaves simple, alternate, apically opposite, or whorled; blade oblanceolate to rarely narrow elliptic; 9.7 – 13.5 × 3.2 – 4.7 cm; apex bluntly apiculate up to 0.7 cm long; base truncate or slightly cordate, margin dentate for distal 1 / 2 to 2 / 3 rd, with distal-pointing glandular teeth; upper and lower surfaces become glabrous at maturity; venation penninerved, nerves 6 – 8 per side, lateral vein angle from 25 – 30 °, looped and joined at 1 – 3 mm from the margin; extrafloral nectaries 2, on basal nerves, elliptic, 1 – 1.5 × 0.3 – 0.5 mm, on the upper surface, sometimes 2 – 6 (– 8) extra ones, elliptic to orbicular, ca. 0.4 × 0.2 – 0.4 mm, along midrib, near the base; petiole sulcate, 0.5 – 3 cm long, covered with stellate hairs. Inflorescences erect, terminal to axillary, unbranched, pubescent with yellow glandular scales, petals, and disc absent. Staminate inflorescence racemes, up to 11 cm long, flowers in groups of up to eight per node; bracts triangular, c. 1 × 0.8 mm. Staminate flowers pedicels 1.3 – 1.5 mm long; sepal 3 – 4, free, ovate, c. 1.7 mm long, densely covered with stellate hairs outside and yellow glandular scales outside and inside; stamens 28 – 33, filaments 1 – 1.5 mm, thecae two separated by broad connective, ovoid to ellipsoid, 0.2 – 0.25 × 0.15 – 0.2 mm, extrorse, opening lengthwise; pistillode present, consisting of 2 – 3 wart-like appendices. Pistillate inflorescences racemose, up to 9 cm long, bracts triangular, c. 0.8 × 1 mm. Pistillate flowers c. 1.5 mm in diameter; pedicel up to 1 mm long; sepal 3, ovate, ca. 1 mm long, free; ovary 3 - locular, hairy, green; style absent to 0.4 mm long; stigmas 3, plumose, up to 1.5 mm long, persistent. Infructescence up to 17 cm long, peduncle 2 – 3 cm long. Fruits 3 - lobed capsules, curved downward when mature, green, subglobose (slightly flattened dorsiventrally), without spines, 0.8 – 1.2 mm in diameter, 3 - locular, densely hairy, and yellow glandular scales, opening into three valves, septicidally and incompletely loculicidally from the base, each valve slightly flattened dorsoventrally, wall ca. 0.7 mm thick. Seeds subglobose, ca. 5 × 4 × 5 mm, ecarunculate, surface smooth, brown.	en	Kim Thanh, Nguyen Thi, Anh, Nguyen Diep, Anh, Tran Thi Thuy, Thuy, La Thi, Duc, Nguyen Anh, Long, Tran Duc, Dang, Van-Son (2025): Mallotus thinii (Euphorbiaceae), a new species discovered from the coastal areas of the south-central provinces of Vietnam. PhytoKeys 265: 193-208, DOI: 10.3897/phytokeys.265.166360
A8FFA03204C15EAEB01157C7E101BEB7.taxon	distribution	Distribution. This species is known from the coastal areas of south-central Vietnam: Sa Huynh beach in Sa Huynh commune, Quang Ngai province; Dang Vinh Loi beach of Phu My commune, Binh Dinh province; and Binh Ba Island of Nam Cam Ranh commune, Khanh Hoa province (Fig. 3).	en	Kim Thanh, Nguyen Thi, Anh, Nguyen Diep, Anh, Tran Thi Thuy, Thuy, La Thi, Duc, Nguyen Anh, Long, Tran Duc, Dang, Van-Son (2025): Mallotus thinii (Euphorbiaceae), a new species discovered from the coastal areas of the south-central provinces of Vietnam. PhytoKeys 265: 193-208, DOI: 10.3897/phytokeys.265.166360
A8FFA03204C15EAEB01157C7E101BEB7.taxon	etymology	Etymology. The species is named in honor of Professor Nguyen Nghia Thin from VNU University of Science, who devoted his career to revising the Euphorbiaceae of Vietnam.	en	Kim Thanh, Nguyen Thi, Anh, Nguyen Diep, Anh, Tran Thi Thuy, Thuy, La Thi, Duc, Nguyen Anh, Long, Tran Duc, Dang, Van-Son (2025): Mallotus thinii (Euphorbiaceae), a new species discovered from the coastal areas of the south-central provinces of Vietnam. PhytoKeys 265: 193-208, DOI: 10.3897/phytokeys.265.166360
